The Night Sky February 2018

Compiled by Ian Morison

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This page, updated monthly, will let you know some of the things that you can look out for in the night sky. It lists the phases of the Moon, where you will see the naked-eye planets and describes some of the prominent constellations in the night sky during the month.

New

which, over time, will provide useful and, I hope, interesting articles for all amateur astronomers. A further aim is to update and add new material to link with the books recently published by Cambridge University Press and which are described on the home page of the digest. It now includes nearly 40 illustrated articles.

Image of the Month

The Cartwheel Galaxy Image HST- NASA/ESA

This is a Hubble Telescope image of the Cartwheel Galaxy which lies some 500 million light years away in the constellation Sculptor. The galaxy's rim is 150,000 light years across and is composed of newly formed massive stars (which are blue in colour). It is thought that the galaxy was initially a spiral and that the ring-like shape is the result of the gravitational disruption caused by the passage of a small intruder galaxy. This has been identified and now lies about 250,000 light years away.

Highlights of the Month

February 8th before dawn: A waning Moon close to Jupiter - with Mars nearby.

The Moon and Jupiter in the pre-dawn sky.

If clear before dawn on the 8th, a waning moon between Full Moon and Last Quarter lies close to Jupiter. Down to the left is Mars lying above Antares in Scorpius.

February 9th before dawn: Mars and a waning Moon.

Mars below a waning Moon

If clear before dawn on the 9th and looking to the South-southeast, Mars, at magnitude +1, will be seen to the lower right of a waning crescent Moon.

February 17th after sunset: Venus and a thin crescent Moon

Venus and a thin crescent Moon.
Image:Stellarium/IM

Looking West-Southwest after sunset on the 17th and given a very low western horizon, one might be able to spot Venus at the start of its new evening apparition. A very thin crescent Moon, just two days after new, will be seen up to its left. Binoculars may well be needed, but please do not use them before the Sun has set. A very tough observing challenge!

February 23rd/24th evening: The Moon in a beautiful skyscape

In the evenings of the 23rb and 24th of the month, the Moon, coming towards first quarter, will pass through Taurus and Orion. On the 23rd, it will lie close to Aldebaran and on the 24th lie above Orion.

February 6th and 22nd evening: The Hyginus Rille

Hyginus Rille location: IM.

For some time a debate raged as to whether the craters on the Moon were caused by impacts or volcanic activity. We now know that virtually all were caused by impact, but it is thought that the Hyginus crater that lies at the centre of the Hyginus Rille may well be volcanic in origin. It is an 11 km wide rimless pit - in contast to impact craters which have raised rims - and its close association with the rille of the same name associates it with internal lunar events. It can quite easily be seen to be surrounded by dark material. It is thought that an explosive release of dust and gas created a vacant space below so that the overlying surface collapsed into it so forming the crater.

Hyginus Crater and Rille

M109 imaged with the Faulkes Telescope

Messier 109
Image: Daniel Duggan Faulkes Telescope North.

The Galaxy M109, imaged by Daniel Duggan. This image was taken using the Faulkes Telescope North by Daniel Duggan - for some time a member of the Faulkes telescope team. It shows the barred spiral galaxy M109 that lies at a distance of 83 million light years in the constellation of Ursa Major. It is the brightest galaxy in the Ursa Major group of some 50 galaxies. Our own Milky Way galaxy is now thought to be a barred spiral like M109.

Observe the International Space Station

The International Space Station and Jules Verne passing behind the Lovell Telescope on April 1st 2008.
Image by Andrew Greenwood

Use the link below to find when the space station will be visible in the next few days. In general, the space station can be seen either in the hour or so before dawn or the hour or so after sunset - this is because it is dark and yet the Sun is not too far below the horizon so that it can light up the space station. As the orbit only just gets up the the latitude of the UK it will usually be seen to the south, and is only visible for a minute or so at each sighting. Note that as it is in low-earth orbit the sighting details vary quite considerably across the UK. The NASA website linked to below gives details for several cities in the UK. (Across the world too for foreign visitors to this web page.)

Note: I observed the ISS three times recently and was amazed as to how bright it has become.

The Moon

The Moon at 3rd Quarter. Image, by Ian Morison, taken with a 150mm Maksutov-Newtonian and Canon G7.Just below the crator Plato seen near the top of the image is the mountain "Mons Piton". It casts a long shadow across the maria from which one can calculate its height - about 6800ft or 2250m.

A World Record Lunar Image

The 9 day old Moon.

To mark International Year of Astronomy, a team of British astronomers have made the largest lunar image in history and gained a place in the Guinness Book of Records! The whole image comprises 87.4 megapixels with a Moon diameter of 9550 pixels. This allows details as small as 1km across to be discerned! The superb quality of the image is shown by the detail below of Plato and the Alpine Valley. Craterlets are seen on the floor of Plato and the rille along the centre of the Alpine valley is clearly visible. The image quality is staggering! The team of Damian Peach, Pete lawrence, Dave Tyler, Bruce Kingsley, Nick Smith, Nick Howes, Trevor Little, David Mason, Mark and Lee Irvine with technical support from Ninian Boyle captured the video sequences from which 288 individual mozaic panes were produced. These were then stitched together to form the lunar image.

Plato and the Alpine Valley.

Please follow the link to the Lunar World Record website and it would be really great if you could donate to Sir Patrick Moore's chosen charity to either download a full resolution image or purchase a print.

The Planets

A montage of the Solar System. JPL / Nasa

Jupiter

A Cassini image of Jupiter . Nasa

Jupiter rises around 2 am at the beginning of the month and just before midnight by month's end. Initially it has a 36 arc second disk, shining at a magnitude of -2 but as the month progresses, its apparent diameter increases to 39 arc seconds and it brightens to magnitude -2.2. Jupiter will transit before dawn and so will enable the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Gallilean moons visible in a small telescope. Sadly, Jupiter, lying in Libra during the month, is heading towards the southern part of the ecliptic and will only have an elevation of ~20 degrees when crossing the meridian. Atmospheric dispersion will thus hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

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Saturn

The planet Saturn. Cassini - Nasa

Saturn, at the start of its new apparition, rises at around 5 am at the start of the month and just after 3 am at its end. With an angular size of ~15.5 arc seconds it climbs higher before dawn and so becomes easier to spot as the month progresses. Its brightness remains at +0.6 magnitudes. The rings were at their widest a few months ago and are still, at 26 degrees to the line of sight, well open. Saturn, lying in Sagittarius, is just 3 degrees above the topmost star of the 'teapot'. Sadly, even when at opposition later in the year it will only reach an elevation of just over 15 degrees above the horizon when crossing the meridian. Atmospheric dispersion will thus greatly hinder our view and it might be worth considering purchasing the ZWO Atmospheric Dispersion Corrector to counteract its effects.

Mercury

Messenger image of Mercury Nasa

Mercury passes through superior conjuction (between us and the Sun) on the 17th February so will be lost in the Sun's glare until the very end of the month when it might just be glimpsed after sunset with its ~5 arc second disk having an unusually bright magnitude of -1.5.

Mars

Mars starts the month moving quicky eastwards in Scorpius close to Beta Scorpii (Graffias) but moves into Ophiuchus on the 8th of the month. Now a morning object at the start of its new apparition, it rises four hours or so earlier than the Sun. During the month, Mars has a magnitude which increases from +1.2 to +0.8 and an angular size of just 5.6, increasing to 6.6, arc seconds so no details will be seen on its salmon-pink surface. It will only reach an elevation of ~14 degrees before dawn at the start of the month and just 12 degrees by month's end.

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Venus

Venus showing some cloud structure

Venus, passed through superior conjunction (on the far side of the Sun) on January 9th and so, at the beginning of February will be lost in the Sun's glare, setting less than half an hour after the Sun. However, by month's end, shining with a magnitude of -3.9, it will set around an hour after the Sun and its 10 arc second disk should be easy to spot 30 minutes or so after sunset. However a low western horizon will be needed as it will then only have an elevation of ~5 degrees some way to the south of west.

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Radar image showing surface features

The Stars

The Mid Evening February Sky

The February Sky in the south-east - mid evening.

This map shows the constellations seen in the south during the evening. The brilliant constellation of Orion is seen in the south. Moving up and to the right - following the line of the three stars of Orion's belt - brings one to Taurus; the head of the bull being outlined by the V-shaped cluster called the Hyades with its eye delineated by the orange red star Aldebaran. Further up to the right lies the Pleaides Cluster. Towards the zenith from Taurus lies the constellation Auriga, whose brightest star Capella will be nearly overhead. To the upper left of Orion lie the heavenly twins, or Gemini, their heads indicated by the two bright stars Castor and Pollux. Down to the lower left of Orion lies the brightest star in the northern sky, Sirius, in the consteallation Canis Major. Up and to the left of Sirius is Procyon in Canis Minor. Rising in the East is the constellation of Leo, the Lion, with the planet Saturn up and to the right of Regulus its brightest star. Continuing in this direction towards Gemini is the faint constellation of Cancer with its open cluster Praesepe (also called the Beehive Cluster),the 44th object in Messier's catalogue. On a dark night it is a nice object to observe with binoculars. There is also information about the constellation Ursa Major,seen in the north, in the constellation details below.

The constellation Taurus

Taurus

Taurus is one of the most beautiful constellations and you can almost imagine the Bull charging down to the left towards Orion. His face is delineated by the "V" shaped cluster of stars called the Hyades, his eye is the red giant star Aldebaran and the tips of his horns are shown by the stars beta and zeta Tauri. Although alpha Tauri, Aldebaran, appears to lie amongst the stars of the Hyades cluster it is, in fact, less than half their distance lying 68 light years away from us. It is around 40 times the diameter of our Sun and 100 times as bright.

AAO Image of the Pleiades, M45, by David Malin

To the upper right of Taurus lies the open cluster, M45, the Pleiades. Often called the Seven Sisters, it is one of the brightest and closest open clusters. The Pleiades cluster lies at a distance of 400 light years and contains over 3000 stars. The cluster, which is about 13 light years across, is moving towards the star Betelgeuse in Orion. Surrounding the brightest stars are seen blue reflection nebulae caused by reflected light from many small carbon grains. These relfection nebulae look blue as the dust grains scatter blue light more efficiently than red. The grains form part of a molecular cloud through which the cluster is currently passing. (Or, to be more precise, did 400 years ago!)

VLT image of the Crab Nebula

Close to the tip of the left hand horn lies the Crab Nebula, also called M1 as it is the first entry of Charles Messier's catalogue of nebulous objects. Lying 6500 light years from the Sun, it is the remains of a giant star that was seen to explode as a supernova in the year 1056. It may just be glimpsed with binoculars on a very clear dark night and a telescope will show it as a misty blur of light.

Lord Rosse's drawing of M1

Its name "The Crab Nebula" was given to it by the Third Earl of Rosse who observed it with the 72 inch reflector at Birr Castle in County Offaly in central Ireland. As shown in the drawing above, it appeared to him rather lile a spider crab. The 72 inch was the world's largest telelescope for many years. At the heart of the Crab Nebula is a neutron star, the result of the collapse of the original star's core. Although only around 20 km in diameter it weighs more than our Sun and is spinning 30 times a second. Its rotating magnetic field generate beams of light and radio waves which sweep across the sky. As a result, a radio telescope will pick up very regular pulses of radiation and the object is thus also known a Pulsar. Its pulses are monitored each day at Jodrell Bank with a 13m radio telescope.

The constellation Orion

Orion

Orion, perhaps the most beautiful of constellations, will be seen in the south at around 11 - 12 pm during January. Orion is the hunter holding up a club and shield against the charge of Taurus, the Bull up and to his right. Alpha Orionis, or Betelgeuse, is a read supergiant star varying in size between three and four hundred times that of our Sun. The result is that its brightness varies somewhat. Beta Orionis, or Rigel, is a blue supergiant which, at around 1000 light years distance is about twice as far away as Betelgeuse. It has a 7th magnitude companion. The three stars of Orion's belt lie at a distance of around 1500 light years. Just below the lower left hand star lies a strip of nebulosity against which can be seen a pillar of dust in the shape of the chess-board knight. It is thus called the Horsehead Nebula. It shows up very well photographically but is exceedingly difficult to see visually - even with relativly large telescope.

The Horsehead Nebula: Anglo Australian Observatory

Beneath the central star of the belt lies Orion's sword containing one of the most beautiful sights in the heavens - The Orion Nebula. It is a region of star formation and the reddish colour seen in photographs comes from Hydrogen excited by ultraviolet emitted from the very hot young stars that make up the Trapesium which is at its heart. The nebula, cradling the trapesium stars, is a beautiful sight in binoculars or, better still, a telescope. To the eye it appears greenish, not red, as the eye is much more sensitive to the green light emitted by ionized oxygen than the reddish glow from the hydrogen atoms.

The Orion Nebula: David Malin

The constellation Ursa Major

Ursa Major

The stars of the Plough, shown linked by the thicker lines in the chart above, form one of the most recognised star patterns in the sky. Also called the Big Dipper, after the soup ladles used by farmer's wives in America to serve soup to the farm workers at lunchtime, it forms part of the Great Bear constellation - not quite so easy to make out! The stars Merak and Dubhe form the pointers which will lead you to the Pole Star, and hence find North. The stars Alcor and Mizar form a naked eye double which repays observation in a small telescope as Mizar is then shown to be an easily resolved double star. A fainter reddish star forms a triangle with Alcor and Mizar.

Ursa Major contains many interesting "deep sky" objects. The brightest, listed in Messier's Catalogue, are shown on the chart, but there are many fainter galaxies in the region too. In the upper right of the constellation are a pair of interacting galaxies M81 and M82 shown in the image below. M82 is undergoing a major burst of star formation and hence called a "starburst galaxy". They can be seen together using a low power eyepiece on a small telescope.

M81 and M82

Another, and very beautiful, galaxy is M101 which looks rather like a pinwheel firework, hence its other name the Pinwheel Galaxy. It was discovered in1781 and was a late entry to Messier's calalogue of nebulous objects. It is a type Sc spiral galaxy seen face on which is at a distance of about 24 million light years. Type Sc galaxies have a relativly small nucleus and open spiral arms. With an overall diameter of 170,000 light it is one of the largest spirals known (the Milky Way has a diameter of ~ 130,000 light years).

M101 - The Ursa Major Pinwheel Galaxy

Though just outside the constellation boundary, M51 lies close to Alkaid, the leftmost star of the Plough. Also called the Whirlpool Galaxy it is being deformed by the passage of the smaller galaxy on the left. This is now gravitationally captured by M51 and the two will eventually merge. M51 lies at a distance of about 37 million light years and was the first galaxy in which spiral arms were seen. It was discovered by Charles Messier in 1773 and the spiral structure was observed by Lord Rosse in 1845 using the 72" reflector at Birr Castle in Ireland - for many years the largest telescope in the world.

M51 - The Whirlpool Galaxy

Lying close to Merak is the planetary nebula M97 which is usually called the Owl Nebula due to its resemblance to an owl's face with two large eyes. It was first called this by Lord Rosse who drew it in 1848 - as shown in the image below right. Planetary nebulae ar the remnants of stars similar in size to our Sun. When all possible nuclear fusion processes are complete, the central core collpses down into a "white dwarf" star and the the outer parts of the star are blown off to form the surrounding nebula.